David Alexander, analyst at retail researcher Conlumino, applauded Primark’s strategy of focusing on “one corner of the USA, eschewing prime locations like Manhattan, to ensure that it meets consumer expectations in the States head-on before rolling out nationwide”.

Rapid international expansion boosted total sales at Primark, which has 287 stores, by 15% to £2.5bn at a constant exchange rate (12% at the actual rate) in the six months to 28 February. Operating profits powered 11% ahead to £322m at constant exchange rates (8% at actual rates).

However, on a like-for-like basis sales were flat in the first half. The retailer blamed the unseasonably warm weather across northern Europe last autumn, along with the impact that new stores in the Netherlands and Germany had on existing shops.

Weston said Primark had doubled the number of stores in the Netherlands and increased its German outlets from 11 to 16.

He said that like-for-like sales in the UK were up 3% as the chain had bounced back over Christmas from a warm autumn and that customers were responding well to spring fashions including bohemian dresses, bracelets and hats.

“There are a lot of discounts on the high street and that’s not just the end of autumn winter, that’s new season, so it’s clearly been tough. Last year was unusually good as it was very warm very early and it got everyone into the habit of buying spring summer. This year is not bad but the warm weather has come later,” he said.

Alexander talked of “another barnstorming performance from wallet-friendly, fast-fashion kingpin Primark”. He said: “The group’s like-for-like performance naturally excludes trading from stores opened over the past 12 months, which includes its entire French operation, as well as stores in Berlin, Stuttgart and Cologne, all of which, Primark claims, feature in its top 20 performers on an annualised sales basis.

“The retailer has defied the naysayers to become a firm favourite across its burgeoning European empire. Such has been the alacrity with which Spanish, French, Dutch and German consumers have taken to Primark that it has become a real disruptor on the fashion scene right across its territories.”

Spain, Portugal and Ireland performed very strongly. Primark plans to open more stores – or extensions to existing shops – in Germany, Belgium and the UK in the coming months. Total new selling space this year will be under 1m sq ft, compared with 1.5m sq ft planned for the next financial year.

Like other retailers such as H&M, Primark has been hit by the strengthening US currency because it buys many of its garments in dollars but sells them in euros and sterling. The continued impact of the stronger dollar will drive up costs for the autumn-winter season. The group indicated it would not pass on these costs to customers, which means profit margins could be hurt.

Weston warned: “If the current euro weakness against sterling and the US dollar persists, this will have an impact on the group’s operating profit for the remainder of this financial year and a greater impact next year.”

Jon Copestake, chief retail analyst at the Economist Intelligence Unit, said: “Primark are doing great and delivering consistent growth while ABF continues to struggle with sugar prices. Consumers are polarised between bargain prices for basic clothes and trading up for more showy clothes – this may change, and Primark’s foray into markets like the USA adds an element of future risk.”

At Primark’s owner, ABF, profits before tax halved to £213m. Higher profits at the discount retailer partly offset a sharp drop in profits at the group’s sugar division due to much weaker EU sugar prices.